Machines of this type generally comprise a large number of winding stations formed by parallel spindles rising from a common bed, each spindle being spacedly surrounded by a coaxial track ring carrying a traveler through which the filament to be wound upon its cop is threaded. The track rings are mounted on a common shelf, or ring bank, which is vertically reciprocable with reference to the spindle bed in order to distribute the turns of the filament as uniformly as possible along the cop surface.
In the operation of such machines, the feeding of the filaments to the several spindles is frequently interrupted by a rupture which may be due to an actual breaking of the thread or to the fact that the thread of an associated supply spool has run out. Since a loose thread end remaining on an incompletely wound and still rotating cop may become entangled with the filaments of adjoining winding stations, it is customary to provide the machines with automatic thread monitors on carriages traveling along the bank of spindles in order to detect the presence of a rupture. These conventional thread monitors automatically arrest any spindle found to have a loose thread end, that end being then picked up by a suction tube and led to a tying mechanism which automatically connects it with a fresh oncoming thread. Before the winding station involved can resume its normal operation, however, it is necessary to reintroduce the previously ruptured thread into the associated traveler.
Systems are already known which automatically carry out this rethreading of a traveler. In these systems, the loose filament end drawn away from the cop by the suction tube is gripped at an intermediate point and bent into two angularly adjoining passes, one of them coming to lie on a flange of the track ring engaged by the traveler while the other pass approaches the ring more or less tangentially so as to cross the path of the traveler driven around the flange by a circulating air stream. It may happen, however, that the traveler finds itself trapped in a dead zone between the two passes, encompassing perhaps a segment of 50.degree. to 80.degree. of the ring periphery, being thus prevented by the first pass from reaching its point of engagement with the second pass. A temporary withdrawal of the thread from the track ring then becomes necessary in order to let the traveler move on whereupon the rethreading operation can be tried anew.